Accumulation and Loss of Cobalt and Cesium by the Marine Clam, Mya Arenaria, Under Laboratory and Field Conditions.

Abstract

The accumulation ol Co and Cs by clams was followed in the laboratory in aquarium systems in which the levels of radioactive and stable cesium and cobalt were held constant. At 3-to 21-day intervals during the 6-month accumulation period, groups of 8 animals were removed from the water and their soft tissues were dissected into 7 different organs and tissues. The concentrations of both Co and Cs in the edible tissues increased rapidly and then levelled off at concentrations of Co that were about 200 times that of Che water and of Cs that were about 5 times that of the water. Variations in concentration among the body parts werf-larger for 60 Co than for 137 Cs.The effect of stable element concentration in water on the accumulation rates were assessed in groups of animals maintained in seawater containing 0. 5, 2. 5, and 12. 5 |j.gAitre each of stable cobalt and cesium. Little regulation of cesium accumulation was observed at these concentrations; the rates of accumulat ; on increased with the concentration in water. Some regulation of cobalt occurred at the high<_i concentrations. I he accumulation of Co and Cs was followed also in clams introduced into a discharge canal receiving radioactive waste from a boilingwater reactor. Groups of 6 animals were sampled at 3-week intervals and concentrations were measured in the pooled, total soft tissues. Results obtained in the field will be compared to those obtained in the laboratory. Loss ofCo and Cs was followed in animals that had accumulatrd a radioactive burden in the laboratory and then were transferred to unfiltered -2-oceanic water at a marine station. Loss of Co by the whole clam was 137 monophasic, that of Cs was biphasic.The kinetics of accumulation and loss were described by exponential equations. The rate constants of accumulation and toss and the steady-state concentration factors are being used in models to predict the dose to man from the consumption of animals exposed to radioactive releases.

Modeling radiocesium bioaccumulation in a marine food chain

“…Rapid turnover of radiocesium was also found in many bivalve species (Bryan 1963, Harrison 1972, Cranmore & Harrison 1975. Similarly, Warnau et al (1996) reported that the depuration rate constant of radiocesium in the echinoid Paracentrotus lividus was 0.116 d -1…”

Feces of intertidal benthic invertebrates: influence of particle selection in feeding ace element concentration

“…A concentration of trace metals in mucus substances expelled with the pseudofeces may contribute to the relatively higher concentrations found in pseudofeces (Table 2), particularly the mucilaginous material produced by Mya arenaria. Mucus sheets on oyster gills have been shown to concentrate trace metals (Korringa 1952, Brooks & Rumsby 1965 and Harrison (1972Harrison ( , 1973 found 65Zn, 60Co and 13'Cs were concentrated in the mucopolysaccharide/proteinaceous 'peel' covering the siphons and mantle margin of Mya arenaria.…”

Uptake, retention and organ/tissue distribution of 137Cs by Japanese catfish (Silurus asotus Linnaeus)

“…In addition, they are present in effluents from nuclear reactors, fuel fabrication, reprocessing and radioisotope production facilities and other activities such as the use of radioisotopes in medicine, industry and agriculture (Weiss and Shipman, 1957;Klement, 1965;Harrision, 1972;Roberson et al,1972;van Weers, 1975;Blaylock et al, 1982;Pinder et al, 1984;Carvalho, 1987). Among the radionuclides, radiocesium, an anthropogenic fission product, has drawn utmost attention for its long physical half-life, high fission yield (Folsom et al, 1968;Folsom and Grismore, 1970;Young et al, 1975;UNSCEAR, 1982;Yamada and Nagaya, 1998) and high bioavailability (Whicker and Schultz, 1982).…”